Condensation after loft insualtion

potts8

In March this year we decided to take up Npower on an offer for free loft insulation thinking there will be great benefits for a warmer house.
As our house was built in 1980 it has bitumen felt lining the roof and it now seems that we have a big problem with condensation forming and now dripping onto the floor.
We do what we can with regards to ensuring extractor fans are always on in the bathroom and try to keep drying clothes on radiator to a minimum ut clearly the house still isn't breathing properly.


I believe the housebuilders installed 75mm insualtion as that was originally however this was tucked down into the majority of the eaves so I'm wondering how much this is contributing to the issue?


Yesterday I was up there pulling it out of the eaves hoping this would assist the airflow so I'll be keeping my eyes on how it goes from today however I'm tempted to even get rid of all the extra insulation and go back to the standard 75mm.


Anyone else had similar issues and did you decide to get rid of the extra insulation or go down the route of paying for extra ventilation?

matelodave

You are doing the right thing, by keeping the eves clear - you may even need to increase the ventilation a bit by adding extra vents - you can get circular soffit ventilators which are easy to fit with a hole cutter.
see here http://www.glidevale.com/soffit-ventilators/p/4 or these from Screwfix https://www.screwfix.com/p/circular-soffit-vent-white-70mm-10-pack/68936

FreeBear

potts8 wrote: »

I'm tempted to even get rid of all the extra insulation and go back to the standard 75mm.

The more insulation, the better. As an absolute minimum, 200mm would be just about acceptable. Dropping down to just 75mm, you will lose quite a bit of heat through your ceilings.

Blot

I cured mine by finding the joins in the roof felting and then at intervals slipping pieces of 2" cardboard tube rolls into the overlaps of the felting. this allowed enough ventilation for the moisture laden air to escape . As it was above the roof insulation laid over the joists, integrity of the insulation was not impaired. At lot of moisture in the house comes from cooking washing and straightforward exhalation from our bodies and needs to be allowed to escape when houses are well wrapped.

Michaelw

It does sound like the soffit's are blocked and in a 1980 house it probably might not have vents or needed them added is about an adequate air flow/temperature.Vent roof tiles can help also.On some properties' a vacuum can occur in the loft space lifting both the loft hatch and roof tiles' in a storm which happend here the developer at the time warned against bloocking vents because of condensation.

potts8

Thank you for the replies so far. From what I can see there are currently no ventilation, soffits or tiles on roof.
I've decided to order some of the lap vents to give them a go as it seems like an easy DIY job and most people report that it works really well: https://manthorpebuildingproducts.co.uk/product/g630-felt-lap-vent


Ideally I shouldn't be removing insulation but I think it was just a gut reaction to being dismayed at my luck with this house so far


I've had a dehumidifier up there for a few hours which seems to have helped alongside ensuring a gap with the insulation.


Once the vents are installed I'll report back with how it's going.


Interestingly I also checked the neighbours house who has the same build and also had the insulation done at the same time as me and they have the same issue so I suspect it's just a lack of any ventilation on these houses built at that time.

Blot

Thing is that when those houses were built the loft insulation was minimal, therefore the air in the roof space was relatively warm and held the moisture. Now having put in better insulation the contained air is cold and cannot hold the same amount of water, hence the condensation . The answer is yes , improve the ventilation and the issue will go away.